#!/bin/bash

#
# Copyright (C) 2007 Karel Zak <kzak@redhat.com>
#
# This file is part of util-linux.
#
# This file is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License or
# (at your option) any later version.
#
# This file is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#

TS_TOPDIR="${0%/*}/../.."
TS_DESC="system to hw"
NTP_SERVER="0.fedora.pool.ntp.org"

. "$TS_TOPDIR"/functions.sh
ts_init "$*"

ts_check_test_command "$TS_CMD_HWCLOCK"

ts_skip_nonroot
if [ "$TRAVIS_DIST" == "precise" ]; then
	ts_skip "https://github.com/util-linux/util-linux/issues/1082"
fi
if [ "$GITHUB_ACTIONS" == "true" ]; then
	ts_skip "virtual machine"
fi

ts_check_prog "bc"
ts_check_prog "sntp"

function get_offset_sys_ntp
{
	local ip="$@"
	local out

	# using hostname instead of IP could give us more than one offset
	out=$(sntp --timeout 1 "$ip") || return 1

	# sed must deliver a signed float or empty string for sure
	out=$(echo "$out" | \
		sed -n 's/.* \(\(+\|-\)[0-9]\{1,\}\.[0-9]\{1,\}\).*/\1/1p')

	[ -n "$out" ] || return 1
	echo "$out"
}

function check_diff_offset
{
	local a=${1#+}
	local b=${2#+}
	local max="$3"
	local tmp

	tmp=$(echo "$a - $b" | bc | tr -d '-')
	echo "$tmp"

	tmp=$(echo "$tmp < $max" | bc)
	[ $tmp -eq 1 ]
}


# we need fixed ntp IP to get comparable offsets
NTP_IP=$(ts_resolve_host "$NTP_SERVER") \
	|| ts_skip "can't resolve hostname $NTP_SERVER"

OFFSET_A=$(get_offset_sys_ntp "$NTP_IP") \
	|| ts_skip "can't get ntp offset 1st, $NTP_IP"
OFFSET_B=$(get_offset_sys_ntp "$NTP_IP") \
	|| ts_skip "can't get ntp offset 2nd, $NTP_IP"

diff=$(check_diff_offset $OFFSET_A $OFFSET_B 0.02) \
	|| ts_skip "unreliable ntp or sys clock offsets: $NTP_IP $OFFSET_A $OFFSET_B +/-$diff"

# hwclock --show should work if we have a hw clock
tmp=$($TS_CMD_HWCLOCK --show 2>&1)
if [ $? != "0" ]; then
	echo "$tmp" | grep -q "Cannot access the Hardware Clock via" \
		&& ts_skip "no hardware clock found"
	ts_failed "hwclock --show"
fi

# call hwclock
for i in `seq 1 10`; do
	# only *skip* on failure for now
	$TS_CMD_HWCLOCK --systohc || ts_skip "hwclock --systohc failed, $i"
	$TS_CMD_HWCLOCK --hctosys || ts_skip "hwclock --hctosys failed, $i"
done

OFFSET_C=$(get_offset_sys_ntp "$NTP_IP") \
	|| ts_skip "can't get ntp offset 3rd, $NTP_IP"

diff=$(check_diff_offset "$OFFSET_B" "$OFFSET_C" 1.0) \
	|| ts_failed "offsets $NTP_IP: $OFFSET_B $OFFSET_C +/-$diff"

ts_ok "offsets $NTP_IP: $OFFSET_B $OFFSET_C +/-$diff"
